[llvm] [AArch64][SVE]Add error message in the AsmParser for SVEPattern (PR #82668)

[Paul Walker via llvm-commits]

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@@ -7939,7 +7939,7 @@ ParseStatus AArch64AsmParser::tryParseSVEPattern(OperandVector &Operands) {
 
     auto *MCE = dyn_cast<MCConstantExpr>(ImmVal);
     if (!MCE)
-      return ParseStatus::Failure;
+      return TokError("expected immediate operand");
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paulwalker-arm wrote:

Given the rational for the fix the chances are the `#` is erroneous rather than the user really wanting to use the `#imm` syntax so for consistency I suggest we emit the same `invalid operand for instruction` message we use for predicate pattern typos.  If at a later date we want to be more expressive then we can fix all instances at the same time.

https://github.com/llvm/llvm-project/pull/82668